1. Field of the Invention
This invention relates, generally, to locking devices and more particularly to means for locking a hydraulic piston rod in an extended condition.
2. Description of the Prior Art
Heavy machinery such as bulldozers and backhoes often remain on the job site throughout the course of a construction project because the effort to transport the equipment to a secure site is expensive and time-consuming. The heavy machinery may be left on a job site for several days. The machinery is relatively unlocked and susceptible to theft and vandalism.
Buckets, blades and like attachments of heavy machinery operate using hydraulic cylinder and piston rod assemblies. The piston rod is retracted and extended from the cylinder using hydraulic pressure. During maintenance, a steel sleeve is commonly interposed between the connection point, or bearing, of the rod and the cylinder opening encircling the exposed piston rod. This supports the rod in an extended position so that in the event of loss of hydraulic pressure the rod will not uncontrollably retract within the cylinder thereby preventing undesirable movement of the attachment.
A sleeve can also be used as a locking device. The locking sleeve is similarly placed over the exposed piston rod as in maintenance use but the sleeve is also locked into place using a padlock. This will prevent the sleeve from being removed and thus secure the rod in an extended condition. With the rod in an extended position the attachments can be fixed in either a lowered or raised position making the unauthorized movement of the heavy machinery more difficult.
Prior art hydraulic locking devices include U.S. Pat. No. 4,373,851 to Confoey that describes a split cylindrical sleeve that encloses around the piston rod and includes extended tabs that are locked together using a padlock to prevent removal. The Confoey configuration is susceptible to having the padlock cut off using bolt cutters or broken off using extreme force. It would be desirable if a more secure locking system could be provided to protect against theft and vandalism.
In summary, the needed improvements include a locking device that is easy to install and remove which is also durable and protects against theft and vandalism.
However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified needs could be fulfilled.
The long standing but heretofore unfulfilled need for a locking device for heavy machinery that can be used at unsecured construction sites or storage areas, which can be installed and removed easily, and which is durable, is now provided in the form of a new, useful and non-obvious device.
The novel structure includes a substantially rigid sleeve consisting of a pair of sleeve halves having diametrically opposite longitudinally extending meeting edges wherein said sleeve halves are hingedly connected along a first meeting edge via a hinge means so that said sleeve halves are openable for mounting on an extended piston rod. A locking means is disposed between said sleeve halves at a second opposing longitudinal extending meeting edge for releasably securing said sleeve halves to one another wherein said sleeve is adapted to fit snugly around said piston rod in encircling relation thereto. A half circle portion of an annular flange is disposed on a first end of each of said sleeve halves wherein the diameter of said annular flange is greater than the diameter of a cylinder of said hydraulic cylinder and piston assembly. A half portion of a lock protecting housing is disposed adjacently and in mirrored relation on each of said pair of sleeve halves so that a locking means can be enclosed therein when said sleeve is mounted on said piston rod. An apertured lug extends from and is secured to each of said sleeve halves within said lock protecting housing wherein each said lug is apertured for receiving a locking pin therethrough and said locking pin is releasably secured using said key. An overlying reinforcing band is disposed proximate to a second end of each of said sleeve halves so that stress loads concentrated at said second end are dissipated.
In a preferred embodiment, a commercially available shackleless locking means with a hidden pin assembly secures the sleeve halves to one another.
In a second embodiment, the locking device includes a standard sleeve half that is secured over the extended piston rod with a pin and bracket assembly. The pin and bracket assembly is placed between the transversely spaced first wall and second wall of the sleeve half member so that the extended rod is interposed between the channel-shaped member and the pin and bracket assembly. A similar shackleless locking means as in the first embodiment secures one end of the bracket within the lock so that the pin and bracket assembly cannot be removed from the sleeve half member thereby preventing removal of the sleeve from the extended piston rod.
An important object of the present invention is to provide an improved locking device, for use with heavy machinery that prevents the movement of a hydraulic piston rod and prevents the theft of the machinery.
Another object is to provide a means for attaching the locking device in its proper, functional location without undue effort so that the locking device may be easily installed and removed as needed.
Another object is to provide a locking device suitable for several different heavy machines without modification and which is durable and can withstand unauthorized removal attempts.
These and other important objects, advantages, and features of the invention will become clear as this description proceeds.
It is to be understood that both the foregoing general description and the following detailed description are explanatory and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute part of the specification, illustrate embodiments of the present invention and together with the general description, serve to explain principles of the present invention.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be indicated in the claims.